The Big Picture blog has an amazing collection of interactive before and after photographs of various cities around the world during Earth Hour 2010 last Saturday evening.

Beginning in Sydney, Australia three years ago, Earth Hour has grown into a global observance. States, large organizations and individual people observed Earth Hour 2010 on Saturday March 27th, as homes, office towers and landmarks turned off their lights for an hour starting at 8.30 pm local time to raise awareness about climate change and the threat from rising greenhouse gas emissions. Collected here are a series of before-and-after photographs from this year - which (starting with the second one below) will fade between "on" and "off" when clicked.

I agree with craig's analogy. Looking at the photos, I wonder why the lights need to be on in the first place. Why not have them dark all the time, less 'light pollution', just like in that simpsons episode :) Great images nonetheless.